Apparatus for deflecting gas turbine engine exhaust gases

ABSTRACT

A gas turbine jet propulsion engine has its turbine gas outlet angle and discharge nozzle plane coadapted to discharge the gas efflux from the nozzle at a specific angle to the engine axis. The discharge nozzle plane angle is obtained by merely chamfering the nozzle end face. The nozzle is rotatable about the engine axis and thus, thrust direction can be changed without physical deflection of the gas efflux with its attendant thrust losses.

United States Patent Inventor Stephen L. Bragg Findern, England Appl.No. 5,016

Filed Jan. 22, 1970 Patented Dec. 7, 1971 Assignee Rolls Royce LimitedDerby, England Priority Jan. 31, 1969 Great Britain 5,544/69 APPARATUSFOR DEFLECTING GAS TURBI NE ENGINE EXHAUST GASES 7 Claims, 4 DrawingFigs.

11.8. C1 ..239/265.35, 60/230, l8l/33.222, 244/56 Int. Cl 1364c 15/04Field of Search ..239/265. 19,

[ 56] References Cited UNITED STATES PATENTS 3,392,529 7/1968 Pike etal. ..I8l/33.222 UX 3,495,682 2/1970 Treiber 181/51 PrimaryExaminer-Lloyd L. King Assistant Examiner--Michael Y. MarAttorney-Cushman, Darby & Cushman ABSTRACT: A gas turbine jet propulsionengine has its turbine gas outlet angle and discharge nozzle planecoadapted to discharge the gas eiflux from the nozzle at a specificangle to the engine axis. The discharge nozzle plane angle is obtainedby merely chamfering the nozzle end face. The nozzle is rotatable aboutthe engine axis and thus, thrust direction can be changed withoutphysical deflection of the gas efflux with its attendant thrust losses.

PATENTEU DEC 71971 SHEET 1 BF 2 Saw/MN A. 2:22;

ltorney I This invention concerns gas turbine jet propulsion engines.

According the present invention there is provided a gas turbine jetpropulsion engine having a straight annular jet pipe mounted coaxiallythereon and wherein the turbine gas outlet is fonned so as to dischargegas therefrom into the jet pipe at a first acute angle to the engineaxis measured in a plane lying tangentially of the turbine disc and thejet pipe gas outlet is formed so as to always discharge the gastherefrom at a second, acute angle to said axis, which angle issubstantially similar in magnitude to said first angle and causes thegas to provide a resultant thrust which acts substantially normal to theplane containing the jet pipe outlet.

Preferably the gas discharge angle from the turbine outlet is obtainedby arranging the turbine blades in a position which, combined with thespeed of flow of the gas through the turbine and the rate of rotation ofthe turbine, causes the gas to be discharged from the turbine, into thejet pipe, at said angle.

Preferably the gas discharge angle from the jet pipe is obtained byforming the jet pipe outlet in a plane which lies at an acute angle tothe engine axis.

Preferably the engine and jet pipe are relatively rotatable.

Preferably, though not restrictively, the engine and jet pipe areadapted for mounting within the structure of an aircraft.

Preferably the engine and jet pipe are mounted with their common axis atan acute angle to the axis of the aircraft.

The invention will now be described with reference to the accompanyingdrawings in which:

FIG. I is a pictorial view of an engine and jet pipe.

FIG. 2 is a part section on line 2-2 of FIG. 1.

FIG. 3 is a diagrammatic view of an engine and jet pipe shown in FIG. I.

FIG. 4 is a further diagrammatic view of an engine and jet pipe shown inFIG. 1.

In FIG. 1 a gas turbine jet propulsion engine 10 comprises a compressor,combustion equipment and an expansion turbine 12, in flow series and ofwhich only the expansion turbine 12 is shown.

A jet pipe 14 is rotatably attached to the downstream end of engine 10,that is, downstream relative to the flow of gases through the engine.

Rotation of jet pipe 14 is made possible by the provision of a bearingarrangement in which the engine outer casing 16 forms the inner racethereof and the upstream end of the jet pipe forms the outer racethereof, as indicated at 18. Rotation may be caused by any convenientmeans.

Expansion turbine 12 comprises a plurality of turbine blades 20equiangularly spaced about the rim of a turbine disc 22. Gases from thecombustion equipment expand through the blades 20 and its reactionthereon causes the blades to impart a rotary movement to disc 22 as iswell known. However, the blades of the present invention are set at aparticular angle to the axis of the engine 10 as will be seen in FIG. 2.The setting of the blades thus deflects the gas flowing therethrough andimparts to it a swirling motion, which causes the gas to enter theannulus 24 of jet pipe 14 on a helical path. The fact that jet pipe 14is annular and not merely a hollow cylinder, is important in that theconfining walls of the annulus 24 maintain the gas on its helical pathuntil it reaches the jet pipe outlet 26.

References to FIGS. I, 3 and 4 shows that the outlet 26 is formed bycutting jet pipe 14 at an acute angle to the engine axis, which angle'0", in the present example, is substantially similar in magnitude toangle 0. Thus, as the arrows 25 in FIG. I show, gas flowing from turbine12, at exit angle 0 swirls around the annulus 24 and leaves outlet 26 asshown at 25 substantially normal to the plane containing outlet 26. Inorder to ensure that the gas is still at its maximum or near maximumswirl when leaving outlet 26, the outlet is formed as closely aspossible to turbine 12. This arrangement provides the advantage of avery short, lightweight jet pipe.

The major advantage gained from the arrangement as described is that ondischarge of the as from jet pipe 14 a change in the direction of gasflow IS 0 tamed, relative to its direction of flow through the engine,without having to present a physical obstruction to the gas flow, suchas a deflector wall or bent elbow-type jet pipe. Thus the thrust losseswhich are inevitable when physical deflection is used, are at leastsubstantially obviated. An engine arrangement as described herein istherefore eminently suitable for installation in an aircraft which isrequired to have short and/or vertical takeoff and landing capabilities.The engine and jet pipe would be mounted in the aircraft as shown inFIGS. 3 and 4, that is, with their common axis 30 at an angle 0 to theroll axis of the aircraft, which angle is also similar in magnitude toangle 0.

In this specific example, angle 0 is 45. Reference to the drawings showsthat the gas leaves the turbine 12 at 45 to the engine axis and at 45 toa line drawn tangentially of the turbine. The gas then swirls around theannulus 24 of jet pipe 14 and then passes therefrom substantially normalto the plane containing the outlet 26, but at 45 to the engine axis 30.

Engine 10 would be mounted at an angle 0 (again, similar in magnitude to0) to the roll axis 32 of the aircraft and this means of course that thegas is flowing normally to axis 32 and is thereby providing a downwardlydirected thrust as shown in FIG. 3.

In FIG. 4 engine 10 is still mounted with its axis 30 at 45 to axis 32but jet pipe 14 has been rotated through about axis 30, thus causing gasto flow therefrom, parallel thereto, so providing rearwardly directedthrust for forward propulsion of the aircraft.

It will be seen from the foregoing description that thrust vectoring isachieved with the absolute minimum of moving parts which permits a rigidstructure, and no physical gas deflection means, which substantiallyobviates thrust losses. Furthermore, an engine and jet pipe of the typedescribed are eminently suitable for mounting in the rear of an aircraftfuselage, in which position, the jet pipe may be rotated so as tocontrol the yaw and pitch angles of the aircraft.

What we claim is:

l. A gas turbine jet propulsion engine having a straight annular jetpipe mounted thereon, said engine and said jet pipe having a commonaxis, said engine having a turbine comprising a turbine disc withturbine blades mounted thereon and forming a turbine gas outlet, saidturbine gas outlet being formed to discharge gas therefrom into said jetpipe at a first acute angle to said common axis measured in a planelying tangentially of said turbine disc, and said jet pipe having a jetpipe gas outlet formed to always discharge gas therefrom at a secondacute angle to said common axis, said second acute angle beingsubstantially similar in magnitude to said first acute angle and causingthe gas to provide a resultant thrust which acts substantially normal toa plane containing said jet pipe outlet.

2. An engine as claimed in claim 1 wherein the first, acute angle issubstantially 45.

3. An engine as claimed in claim 1 wherein the second, acute angle issubstantially 45.

4. An engine as claimed in claim 1 wherein the engine and jet pipe arerelatively rotatable.

5. An engine as claimed in claim I wherein at least one said engine isadapted for mounting in an aircraft.

6. An engine as claimed in claim 5 wherein the at least one engine ismounted at an acute angle to the roll axis of the aircraft.

7. An engine as claimed in claim 6 wherein said angle is substantially45.

1. A gas turbine jet propulsion engine having a straight annular jetpipe mounted thereon, said engine and said jet pipe having a commonaxis, said engine having a turbine comprising a turbine disc withturbine blades mounted thereon and forming a turbine gas outlet, saidturbine gas outlet being formed to discharge gas therefrom into said jetpipe at a first acute angle to said common axis measured in a planelying tangentially of said turbine disc, and said jet pipe having a jetpipe gas outlet formed to always discharge gas therefrom at a secondacute angle to said common axis, said second acute angle beingsubstantially similar in magnitude to said first acute angle and causingthe gas to provide a resultant thrust which acts substantially normal toa plane containing said jet pipe outlet.
 2. An engine as claimed inclaim 1 wherein the first, acute angle is substantially 45* .
 3. Anengine as claimed in claim 1 wherein the second, acute angle issubstantially 45*.
 4. An engine as claimed in claim 1 wherein the engineand jet pipe are relatively rotatable.
 5. An engine as claimed in claim1 wherein at least one said engine is adapted for mounting in anaircraft.
 6. An engine as claimed in claim 5 wherein the at least oneengine is mounted at an acute angle to the roll axis of the aircraft. 7.An engine as claimed in claim 6 wherein said angle is substantially 45*.